Flow indicating device and method

ABSTRACT

A device for indicating changes of a fluid flow, comprises a housing (1) and a support member (7), connected with the housing. A valve member (11) is slidable on the support member (7) and is adapted to increase or decrease the through-flow area of a passage (14) provided in the housing for the fluid flow. A spring (13) supported by said support member (7) is urging the valve member to decrease the through-flow area of the passage. Indicating means (15, 16) is arranged to indicate the position of the valve member (11) in the housing. According to the invention, the support member (7) is adjustable relative to the housing in the moving direction of the valve member (11) for adapting the position of the valve member (7) to various magnitudes of fluid flow through the passage (14).

The present invention relates to a device for indicating changes of afluid flow, comprising a housing with an inlet and an outlet for thefluid, means in the housing forming a passage for the fluid on its waybetween said inlet and outlet, a valve member arranged in the housingand displaceable along a path relative to said means to successivelyincrease or decrease the through-flow area of the passage, a supportmember connected with the housing, and a spring arranged between thevalve member and the support member to actuate the valve member todecrease the through-flow area of the passage, the valve member beingmovable along said path by fluid flowing through the passage against theaction of said spring. Said device also comprises indicating meansarranged to indicate the position of the valve member in the housing.The invention also relates to a method of operating such a device.

A device of this kind is disclosed in U.S. Pat. No. 3,881,354. In thisknown device the valve member is adapted to compress a screw spring to acertain degree dependng on the rate of the flow through said passage.Changes of the flow rate in the passage will thus result in changes ofthe compression of the screw spring. By this device it is not possibleto achieve the same high accuracy in indication of a small change of theflow rate at a large flow as at a small flow through the passage. Thereason for this is the varying resistance to compression exerted by thescrew spring at various stages of compression. It would thus benecessary to use different screw springs for various magnitudes of thefluid flow.

An object of the present invention is to provide a flow indicatingdevice of the kind initially described, which is easily adjustable suchthat the same high accuracy can be obtained of an indication of amoderate change of the flow independent of the magnitude of the flow.

According to the invention this object is achieved by means of a devicewhich is characterized in that the support member is adjustable relativeto the housing in the moving direction of the valve member foradaptation of the position of the valve member to various magnitudes offlow through said passage.

In a preferred embodiment of the invention the valve member is guided bythe support member along said path. Preferably the support member isdisplaceable relative to the housing in a direction away from the valvemember against the action of a further spring provided between thesupport member and the housing, said further spring being stronger thanthe spring arranged between the valve member and the support member.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described more closely in the following withreference to the accompaning drawing, which shows, as an example, apartial length section of a device according to the invention.

In the drawing there is shown a housing 1 with an inlet 2 and an outlet3 for a stream of liquid. The housing is provided with a socket 4, inwhich a closure member 5 is fitted. In the closure member 5 there is abore 6, in which a support member in the form of a spindle 7 is axiallyslidable. The spindle is threaded and provided with a nut 8 at its endsituated outside the housing. A disc shaped projection 9 is provided ona spindle portion situated within the housing. Between the projection 9and the closure member 5 there is a screw spring 10 fitted on thespindle. By means of the nut 8 and this spring the position of thespindle can be adjusted axially relative to the housing 1. A valvemember 11 provided with a central bore is slidable on the spindleportion between the projection 9 and the spindle end situated within thehousing 1. Movement of said valve member in a direction away from theprojection 9 is limited by a shoulder 12 at the end of the spindle 7.The valve member 11 is being pressed against the shoulder 12 by a screwspring 13, supported by the projection 9. Coaxially with the valvemember 11 there is arranged a passage 14 in the housing for the flowbetween the inlet 2 and the outlet 3. The valve member 11 preferably hasa parabolically curved surface for co-operation with the means formingsaid passage 14 to change the through-flow area of the latter.

The spindle 7 is provided with a bore axially extending from the spindleend situated outside the housing 1 to an end wall near the other end ofthe spindle 7. In the spindle bore there is provided an electric springswitch 15, a so-called reed switch. This co-operates with a magnet 16fixed to the valve member 11. The reed switch 15 is positioned withinthe spindle bore by means of a screw spring 17 and a tube 18 threadedinto the spindle bore. The screw spring 17 is situated between thebottom wall of the spindle bore and the reed switch 15 pressing the reedswitch against one end of the tube 18. The reed switch 15 is to beactuated by the magnet 16 when the valve member has moved a certaindistance from its position at rest on the sholder 12, i.e. at a pointsomewhere between the shoulder 12 and the projection 9. The location ofsaid point is set by turning of the threaded tube 18 such that the reedswitch 15 is moved axially in the spindle bore. Preferably, the locationof said point is set such that the magnet 16 will acutate the reedswitch 15 already when the valve member 11 has moved rather a smalldistance from the shoulder 12. This setting must be performed before theclosure member 5, together with the support member 7 and the valvemember 11, is fitted into the socket 4. The reed switch 15 and themagnet 16 thus constitute an indicating means arranged to indicate theposition of the valve member 11 in the housing 1.

In use, i.e. while liquid is flowing through the housing 1, the deviceis further adjusted as follows: The support member or spindle 7 is movedby means of the nut 8 into a position relative to the housing 1 suchthat the liquid flowing through the passage 14 forces the valve member11 to take a position relative to the spindle, at which the magnet 16actuates the reed switch 15. At a certain decrease of the flow throughthe passage 14 the spring 13 will displace the valve member 11 relativeto the spindle 7 such that the magnet 16 will no longer actuate the reedswitch 15 to indicate the flow. A certain increase of the flow throughthe passage 14 would cause a corresponding cease of actuation as aresult of an oppositely directed movement of the valve member 11relative to the spindle 7.

If the liquid flow through the passage 14 ceases, the valve member 11will of course become seated on the shoulder 12. In this position therewill still be left a smaller or larger through-flow area of the passage14 depending on the magnitude of the liquid flow for which the devicewas once adjusted.

The spring 13 is so much weaker than the spring 10 that it will becompletely compressed by the force of the flowing liquid acting on thevalve member 11, before compression of the spring 10 begins. Thearrangement of the spring 10 is a precaution for a situation in whichthe flow indicating device would not have been adjusted in connectionwith a change to a substantially larger liquid flow. In such a case, thespring 10 will be compressed such that said larger flow will not beobstructed by the valve member. Otherwise, an undesired high pressurecould arise, which could be damaging for equipment connected to the flowindicating device.

I claim:
 1. A method of changing the measuring range of a device forindicating changes of a fluid flow, the indicating device comprising ahousing (1) with an inlet (2) and an outlet (3) for the fluid, means inthe housing (1) forming a passage (14) for said fluid on its way betweensaid inlet (2) and outlet (3), a valve member (11) arranged in thehousing (1) and displaceable along a path relative to said passageforming means to successively increase or decrease the through-flow areaof the passage (14), a support member (7) connected with the housing(1), and a spring (13), which is supported by the support member (7) andarranged between the latter and the valve member (11) to actuate thevalve member (11) to decrease the through-flow area of the passage (14),the valve member (11) being arranged to be moved along said path by thefluid flowing through the passage (14) against the action of said spring(13), said indicating device further comprising indicating means (15,16) arranged to indicate a certain position of the valve member (11)relative to the support member (7), part (15) of said indicating meansbeing connected with the support member (7), the method comprisingmoving the support member (7) relative to the housing (1) in one of theopening and closing directions of the valve member (11) from a firstposition, in which the valve member is adapted for a first fluid flowthrough the indicating device, to a second position in which the valvemember is adapted for a different fluid flow through the indicatingdevice.
 2. A method according to claim 1, in which the support member(7) is moved relative to the housing (1) in one of the opening andclosing directions of the valve member (11) while fluid is flowingthrough said passage (14) until said second position of the valve memberrelative to the support member is obtained.
 3. In a device forindicating changes of a fluid flow and comprising a housing (1) with aninlet (2) and an outlet (3) for the fluid, means in the housing (1)forming a passage 14 for said fluid on its way between said inlet (2)and outlet (3), a valve member (11) arranged in the housing (1) anddisplaceable along a path relative to said passage forming means tosuccessively increase or decrease the through-flow area of the passage(14), a support member (7) connected with the housing (1), and a spring(13), which is supported by the support member (7) and arranged betweenthe latter and the valve member (11) to actuate the valve member (11) todecrease the through-flow area of the passage (14), the valve member(11) being arranged to be moved along said path by the fluid flowingthrough the passage (14) against the action of said spring (13), saidindicating device further comprising indicating means (15, 16) arrangedto indicate a certain position of the valve member (11) relative to thesupport member (7), part (15) of said indicating means being connectedwih the support member (7), the improvement comprising means (8, 10)separate from said housing (1) and said support member (7) formaintaining the support member in various operative positions relativeto the housing aligned with the direction of opening and closing of saidvalve member (11).
 4. A device according to claim 3, characterized inthat said separate means include a nut (8) and a further spring (10),said nut (8) being threaded on an end of the support member (7) situatedoutside the housing (1), and said further spring (10) being providedbetween the support member (7) and the housing (1), so that the supportmember (7) is displaceable relative to the housing (1) in a directionaway from the valve member (11) against the action of said furtherspring (10).
 5. The device according to claim 3, characterized in thatsaid separate means (8, 10) include an element (8) operable from outsidethe housing (1).